Natural Color fill in flash

I was wondering why I get a bit yellowish image if I metered the ambient light of the subject and then set it to 1 stop lower than actual exposure. Flash is bouce flash. Either ETTL or manual flash power( adjusted for correct exposure) still yield a bit yellowish image.

I use 1/25 f4.0 in Manual mode at ISO800 with flash output set to 1/32 bounce from ceiling at 6ft. I use Kelvin balance to 5500K.

If I use 1/60 f4.0 in Manual mode at ISO100 ETTL flash (bounce) , I'll get a bit reddish image. The former is closer to the real color.

Changeing the aparture or shutter speed would not make the background darker.

Probably because either the ambient is tungsten lighting, and / or the walls you are bouncing off aren't neutral.

danielyamseng wrote in post #6006369
I was wondering why I get a bit yellowish image if I metered the ambient light of the subject and then set it to 1 stop lower than actual exposure. Flash is bouce flash. Either ETTL or manual flash power( adjusted for correct exposure) still yield a bit yellowish image.

I use 1/25 f4.0 in Manual mode at ISO800 with flash output set to 1/32 bounce from ceiling at 6ft. I use Kelvin balance to 5500K.

If I use 1/60 f4.0 in Manual mode at ISO100 ETTL flash (bounce) , I'll get a bit reddish image. The former is closer to the real color.

Changeing the aparture or shutter speed would not make the background darker.

This sounds like you are getting the tint with ambient light from incandescent bulbs to me. The fact that when you drop the ambient exposure several stops it shifts from yellowish to red is a huge clue. I imagine you are seeing the tint in the shadows and background.

The ceiling is white and the light source is flourescent light.

There you have the answer (fluorescent)

You'll get a color cast at shutterspeeds that are not including a "full wave" of the mains.
(Mains frequency60Hz: 1/60s > 1/125, 1/60, 1/30 etc. Mains frequency 50Hz: 1/50s > 1/100, 1/50, 1/25 etc. )

And obviously the WB needs to be set to fluorescant, and the flash gelled to match.

René Damkot wrote in post #6010682
There you have the answer (fluorescent)

You'll get a color cast at shutterspeeds that are not including a "full wave" of the mains.
(Mains frequency60Hz: 1/60s > 1/125, 1/60, 1/30 etc. Mains frequency 50Hz: 1/50s > 1/100, 1/50, 1/25 etc. )

And obviously the WB needs to be set to fluorescant, and the flash gelled to match.

That's the part that makes it really all come together. With that you've just made all the light the same color.

Now if I could just get that down as second nature...

WB set to flourescent would yield a slightly bluish image. I guess the flash partly contribute to this. Can I modify the kelvin to compensate for these ambient to flash ration lighting?

Or I had to gel the flash?

danielyamseng wrote in post #6011966
Or I had to gel the flash?

This.

Using a gel on your flash to bring it to the ambient temperature will work. Balancing two widely different light temps is near impossible in most cases.

Your other option is to eliminate ambient and use all flash to light the scene.